Hall detection device for thickness of sheet medium

Abstract

A Hall detection device for a thickness of a sheet medium is provided, including a mounting rack, a reference shaft and a floating wheel assembly, wherein the floating wheel assembly includes a bracket and at least one floating wheel, one end of the bracket being mounted on the mounting rack via a floating wheel rotary shaft and the other end thereof being rotationally fitted with the floating wheel so as to form a free end, a torsional spring is provided between the floating wheel rotary shaft and the bracket so that the floating wheel elastically bears against the reference shaft, and the bracket is fixedly mounted with a detection block and a sensor for detecting a displacement amount of the detection block.

The invention claimed is: 
     
       1. A Hall thickness detection device for a sheet-like medium, comprising:
 a mounting frame, 
 a reference shaft which has two ends mounted to the mounting frame via bearings, and 
 a floating roller assembly, 
 wherein a mounting frame configured to mount and carry the reference shaft and floating roller assembly; 
 wherein the floating roller assembly comprises: 
 a holder, 
 at least one floating roller, wherein one end of the holder is fixedly mounted with respect to the mounting frame through a floating roller rotating shaft, and another end of the holder is rotationally assembled to the floating roller to form a free end, 
 a torsion spring, which is provided between the floating roller rotating shaft and the holder to allow the floating roller to elastically press against the reference shaft, 
 a detection block, which is fixedly mounted to a side, facing away from the floating roller, of the holder; and 
 a sensor, which is opposed to the detection block and fixedly mounted with respect to the mounting frame for detecting displacement of the detection block in a non-contact manner, 
 wherein a connection line between an axial center of the floating roller and an axial center of the reference shaft is in line with a detection center of the detection block and a detection center of the sensor, an elastically pressing point of the floating roller pressing against the reference shaft forms a tangent point, a distance from an axial center of the floating roller rotating shaft to the tangent point is equal to a distance from the axial center of the floating roller rotating shaft to a detection center of a surface of the detection block, and a connection line from the tangent point to the axial center of the floating roller rotating shaft is at an angle of 45 degrees with respect to a direction of a conveying path of the sheet-like medium. 
 
     
     
       2. The Hall thickness detection device for the sheet-like medium according to  claim 1 , wherein the detection block is a circular magnet with a radius of R 2 , and a distance D from a center of the magnet to a detection point of the sensor satisfies D<(⅔)*R 2 . 
     
     
       3. The Hall thickness detection device for the sheet-like medium according to  claim 2 , wherein a distance from the axial center of the floating roller rotating shaft to the tangent point is R 1 , wherein R 1 >10*D. 
     
     
       4. The Hall thickness detection device for the sheet-like medium according to  claim 1 , wherein a distance D from a center of a magnet to a detection point of the sensor is greater than 5 times a standard thickness T of the sheet-like medium. 
     
     
       5. The Hall thickness detection device for the sheet-like medium according to  claim 2 , wherein a distance D from a center of a magnet to a detection point of the sensor is greater than 5 times a standard thickness T of the sheet-like medium.